Miniature 6-Degree of Freedom Hexapod Robotics Positioner

Precision Handling, Testing, Assembly

Miniature hexapod positioners are perfectly suited for precision assembly and alignment applications of small, high precision parts. They provide extremely flexible motion in all degrees of freedom, plus a programmable center of rotation. PI hexapods come with an easy to use controller and software that provides them with motion flexibility similar to the human hand.

PI's H-810 and H-811 miniature 6-Axis positioners combines all advantages of PI’s high load tried and proven parallel-kinematic robot systems in the smallest of packages. With a diameter of only 10 cm and a height of less than 12 cm, the M-810 offers travel
ranges of up to 40 mm in the XY plane and 13 mm in the Z direction. Despite of its small size, the hexapod can reliably position loads of up to 5 kg at velocities of 10 mm/s.

The small envelope was made possible by the usage of new technologies for encoders, motors and reference switches. Nevertheless, the Mini-Hexapod is 100% compatible with PI's tried and proven hexapod controllers and software.

As with other parallel-kinematics positioners from PI, the six high resolution actuators are connected directly to a single moving platform. The user is able to define the center of rotation (pivot point) independent of platform motion with a simple software command.

In contrast to conventional, stacked, multi-axis systems, there is no accumulation of guiding and lever-arm induced errors

Piezo Assemblies for Micro Pumps and Valves

Precison Dosing of Microliter Volumes

Piezo = Miniaturized Technology
Displacement pumps are used worldwide in many diverse branches of industry. Increasing miniaturization means the market for their smaller “relatives“ is also growing: Microdispensers take on distribution and dosing tasks where small volumes in the milliliter, microliter or nanoliter range have to be controlled.

Piezo is the Driving Force
The design is based on the familiar principles of diaphragm pumps and valves and also makes use of the peristaltic principle. The miniaturized drives are based on piezoelectric actuators in various shapes and degrees of integration.

Micro-diaphragm pumps operate in a similar way to piston pumps, but the medium to be transported is separated from the drive by a diaphragm. Passive inlet and outlet valves
control the pumping direction. Piezo ceramic elements in disk form which are mounted directly onto a metal disk make ideal drive systems for micro-diaphragm pumps: This drive solution occupies extremely little space, and the piezo displacement can be very finely adjusted, to nanometers,
allowing the pumped volumes to be very precisely defined.

Adapted for Precision & Force
The properties of the pump media – viscosity and drop size, for example – determine the different forces which have to be applied and hence the size and type of the piezo actuator used. The piezo displacement is a variable parameter which controls the dosing volume. With micropumps, the frequency also determines the flow rate that can be achieved.

The principle of peristaltic pumping makes directional valves obsolete; the pumping direction in this case is specified by the order in which the individual actuator elements are driven.

PiezoMove: Moving, Positioning, Scanning

Piezo linear actuators can be used in micro-valves, particularly where viscous liquids with a tendency towards higher back pressures are processed; where larger strokes of the valve tappet are required, with lever amplification as well.

Piezo = nano precision = expensive?
Piezo actuators provide a lot more benefits than “just“ precision. Their excellent dynamics and high force also play a crucial role in many areas, where nanometer precision is not (yet) required: e.g. for fast switching, vibration cancellation, or to adjust tools in machines.

In these applications the piezo actuator is one – if not the only – solution and in the case of the new Piezo

Move OEM actuators, at a very attractive price. PiezoMove OEM actuators: Apply motion, how and where it is required
PiezoMove actuators combine guided motion and long travel ranges up to 1 mm and provide precision in the 10 nm range if ordered with the position sensor option. They are very compact, easy to integrate, require no maintenance and provide service life of Billions (10exp9) of cyles.

PI supplies a variety of standard integration levels and also customized versions: From simple piezo stack components
and preloaded linear actuators through to 6-axis positioning systems with subnanometer precision.

Electrophysiology: Piezos Enable Faster Solution Switching

Electrophysiological studies require fast motions of a double-
bore (theta-glass) pipette across cell membranes. With a cell held in a patch
clamp and monitored
electrically, one bore of
the pipette flows a buffer
solution, while the other
carries a drug or other
chemical. By quickly
sweeping the pipette so
one bore or the other suffuses
the cell, its electrophysiological
response
can be correlated to the
chemical environment.
Piezos are ideal for fast
switching, as they offer
electromagnetic quietness, good repeatability, high reliability
and fast speeds. However, fast acceleration can
mean recoil forces excite vibration in the pipette and both
piezo and stepper actuators have suffered from these in
the past. These cause unwanted, repetitive solution
switching for many milliseconds. More....

Ultrasonic Piezos Drive Medical Engineering

The continuing miniaturization in medical engineering places ever increasing
demands on the components. Piezo drives are the solution for many
motion control applications; the piezo effect efficiently generates fast
and precise motion while requiring very little space.

Efficient Aerosol Generation with Piezo Elements
The treatment of respiratory diseases often involves medications being administered directly with atomizers. One method of atomization is to generate very fine droplets with the aid of ultrasonic piezo ceramics. Specially shaped piezo disks excite a stainless steel diaphragm with several thousand holes to execute ultrasonic oscillations at more than 100 kilohertz: this produces particularly
homogenous aerosols, allowing the medications to be dosed accurately and administered in a more targeted way.

An ultrasonic piezo ring disk produces the aerosol in the atomizer head of the eFlow® rapid Electronic Nebulizer series.
(source: Pari Pharma GmbH)

Moreover, the piezo technology reduces the time required to atomize medications by up to 50 % compared to conventional systems increasing the quality of life for patients with chronic diseases.

Piezo ceramics meet the special hygiene requirements in medical engineering; the aerosol generators can be sterilized at high temperatures, even in autoclaves. The ultrasonic operation is soundless for humans, and the low power consumption of the piezo components allows battery operation.

Piezoelectric Drives in Microfluidics
Piezo-driven microdispensers, i.e. micropumps and microvalves, can dose minute volumes down to the microliter range with very high accuracy. Disk-shaped piezo elements mounted directly onto a metal microdiaphragm provide the highly dynamic drive for precision miniature liquid or gas pumps. Due to the separation of drive and medium through the diaphragm, interference with the pumped media is completely avoided.

Lab-on-a-chip applications are made possible by the minute dimensions.

Dispensers for Bio-Handling

A single M-664KCEP and a stack of 8 M-664KCEP linear actuators, shown with well plate. The integrated ceramic piezomotor provides high speeds of more than 200 mm/sec.

PI is increasingly employing PILine® piezo ultrasonic drives in its positioning stages as an alternative to motor/lead-

screw designs – particularly when the stages must be small and fast. They achieve positioning accuracies of up to 0.1 µm and speeds of up to several 100 mm/s.

Small and fast is not only a requirement in classical micropositioning technology, however. Piezo ultrasonic motors are also extremely well suited to applications where the accuracy requirements are not quite so demanding – in the range between 5 and 100 micrometers for example, which is usually sufficient for industrial automation and handling tasks.

PI has developed the low cost M-664KCEP dispenser drive with PILine® piezo ultrasonic motors for this kind of application. Eight or more of these drives stacked together can move pipettes vertically and independently of each other in order to dispense liquids into well plates. A single actuator is only 9 millimeters wide to match the standardized sample holder.

The M-664KCEP covers the travel range of 50 millimeters in less than 250 milliseconds and generates forces of up to 4 N. The resolution of the positioning sensor is matched to the application and amounts to 5 micrometers.